<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>
	<script type="text/javascript">
		let arr = [1, 2, 3 ,5 ,7 ] 
		//数组[数组.length] = "" 恒定住数组最后添加一个数组
		arr[arr.length] = "hi"
		console.log(arr)


		// 数组的取赋值
		// 取值
		console.log(arr[2])//4
		arr[2] = "hello"//赋值
		console.log(arr)
	</script>
</body>
</html>